Technical Field
The present invention relates to an optical information reader that optically reads an information code or the like.
Related Art
Conventionally, when an information code, such as a barcode or a QR code (registered trademark), is optically read, reading of the information code is facilitated by a marker light being irradiated onto a reading target to which the information code is attached. The marker light indicates the center of an imaging area.
However, when the center of the imaging area is indicated using the marker light, a problem occurs in that a slight misalignment is present between the actual center of the imaging area and the center of the marker light. This problem becomes more significant as the distance between the reading target and the reader becomes shorter.
A reason this problem occurs is that, when an attempt is made to bring an optical axis of the marker light and an optical axis that is the center of the imaging area closer together, a light receiving sensor and a marker light source are required to be disposed such as to be separated, depending on the sizes of the light receiving sensor and the marker light source, as well as the areas required to mount the light receiving sensor and the marker light source.
To solve this problem, for example, an optical information reader disclosed in JP-A-2009-020722, described below, is known. In this optical information reader, two marker optical systems are provided, one on each side of the light receiving sensor. The light receiving sensor is disposed between a right-side marker optical system and a left-side marker optical system, such as to be positioned on a virtual line connecting an optical axis of the right-side marker light and an optical axis of the left-side marker light. Therefore, a center axis that is the center of the overall marker light including the right-side marker light and the left-side marker light, and a light reception optical axis of the light receiving sensor can be matched. As a result, a readable area and a reading center position of the readable area can be explicitly indicated with accuracy, regardless of the distance between a reading opening and the reading target.
However, in a configuration that requires a plurality of marker light irradiating units (marker light sources), such as that described above, in addition to increase in manufacturing cost due to a larger number of components, a problem occurs in that size reduction of the reader becomes difficult because two marker optical systems are required to be disposed, one on each side of the light receiving sensor.